text: /* An interface to read and write that retries after interrupts.
  
     Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004, 2005, 2006 Free
     Software Foundation, Inc.
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2, or (at your option)
     any later version.
  
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
  
     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software Foundation,
     Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  
  #include <config.h>
  
  /* Specification.  */
  #ifdef SAFE_WRITE
  # include "safe-write.h"
  #else
  # include "safe-read.h"
  #endif
  
  /* Get ssize_t.  */
  #include <sys/types.h>
  #include <unistd.h>
  
  #include <errno.h>
  
  #ifdef EINTR
  # define IS_EINTR(x) ((x) == EINTR)
  #else
  # define IS_EINTR(x) 0
  #endif
  
  #include <limits.h>
  
  #ifdef SAFE_WRITE
  # define safe_rw safe_write
  # define rw write
  #else
  # define safe_rw safe_read
  # define rw read
  # undef const
  # define const /* empty */
  #endif
  
  /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
     interrupted.  Return the actual number of bytes read(written), zero for EOF,
     or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error.  */
  size_t
  safe_rw (int fd, void const *buf, size_t count)
  {
    /* Work around a bug in Tru64 5.1.  Attempting to read more than
       INT_MAX bytes fails with errno == EINVAL.  See
       <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
       When decreasing COUNT, keep it block-aligned.  */
    enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
  
    for (;;)
      {
        ssize_t result = rw (fd, buf, count);
  
        if (0 <= result)
  	return result;
        else if (IS_EINTR (errno))
  	continue;
        else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
  	count = BUGGY_READ_MAXIMUM;
        else
  	return result;
      }
  }
  